1. Field of the Invention
This invention relates to nonwoven surface finishing articles comprising a three-dimensional web and a reinforcing backing formed of a polymer layer. The invention also relates to a method of making the articles involving coating the web with a layer of polymeric material.
2. Prior Art
Nonwoven three-dimensional fibrous abrasive products have been employed to remove corrosion, surface defects, burrs, and impart desirable surface finishes on various articles of aluminum, brass, copper, steel, wood, and the like. Nonwoven, lofty, three-dimensional, fibrous abrasive products made according to the teaching of U.S. Pat. No. 2,958,593 have been in wide use for quite some time. These abrasive products are used in the form of discs and belts, but have the drawback of easily snagging on sharp edges when in the form of endless belts. The belts also do not have sufficient breaking strength for many applications.
Various references teach reinforcing such nonwoven, lofty, three-dimensional abrasive products. U.S. Pat. No. 3,324,609 describes an attempt to reinforce the nonwoven fibrous web by needle tacking the three-dimensional web into a support web. U.S. Pat. No. 3,688,453 discloses another method of reinforcing three-dimensional fibrous webs by needle tacking the web-forming fibers into a reinforcing scrim and then impregnating the resultant structure with a binder containing abrasives. The scrim reinforced nonwoven abrasive products have been widely used but were not stretch resistant for many applications when in the form of a belt. U.S. Pat. No. 4,331,453 discloses delamination resistant abrasive belts and discs comprising a lofty, nonwoven, three-dimensional abrasive web adhesively laminated to a stretch resistant woven fabric with adhesive polyurethane binders. U.S. Pat. No. 4,609,581 discloses a coated abrasive sheet structure wherein a fibrous surface of the backing is coated with a hot melt adhesive to both lock fibers into a support backing and to prepare a smoothed surface for subsequent overcoating with a liquid adhesive and abrasive particles. Although these products were stretch resistant, there still existed a need for a snag resistant, flexible product.
Lofty, fibrous abrasive belts have been developed which are improvements of the articles described in U.S. Pat. Nos. 4,331,453 and 3,688,453. Preferably these three-dimensional, lofty, fibrous abrasive articles are stretch resistant, smooth running, durable and snag resistant. Improved products were made by substitution of a woven cloth for an open mesh cloth employed in U.S. Pat. No. 3,688,453. These improved, stretch resistant, nonwoven abrasive belts were snag resistant and performed well in uses where the belt was supported by a contact wheel against the article being finished. However, in those applications where the belt is supported by a stationary platen, excessive friction between the fibers protruding through the woven cloth and the platen caused excessive abrasion and heating of the platen. As a result, this belt operated in a jerky fashion which produced an inconsistent surface finish on the article being finished and caused excessive wear of the platen. There exists a need for an abrasive article without fibers protruding from the backside of the article.
In spite of the aforementioned patents, there exists a need for a durable, snag resistant, stretch resistant, low friction, fiber-free back, fibrous abrasive or polishing product.